LI Xiao-hong, XIE Yong-hui, ZHONG Qun-peng, CAO Chun-xiao. Study on Microstructure and Mechanical Properties of DD3 Single Crystal Alloy Joints Bonded for Short Time[J]. Journal of Materials Engineering, 2005, 0(5): 3-6,10.
Single crystal superalloy DD3 was diffusion bonded at 1250℃ for 10,30min,1,2,4h with two interlayer alloys D1P and D1F.The compositions of these two interlayer alloys are similar to those of DD3 substrate and boron was added as melting-point depressant.The microstructures and mechanical properties of the joints were examined.Results showed that holding for such short time,there were a lot of blocky γ'phases in the bonding seam with D1P interlayer alloy,causing a lower stress rupture property of about 60% of the DD3 substrate at 980℃.However,for the D1F interlayer alloy,homogenious joint microstructures were obtained showing a higher stress rupture property of about 70% of the DD3 substrate at 980℃.
HUANG Xiao-ting, WANG Fu-chi, MA Zhuang, WANG Quan-sheng. Study on Process,Microstructure and Properties of Surface Graded Coating on C/PMR15 Composite[J]. Journal of Materials Engineering, 2005, 0(5): 7-10.
Two surface graded coatings on C/PMR15 substrate,Ni-Ni/Cr-WC/Co and PI-Ni/Cr-WC/Co were designed.Microstructure and the ability of resistance thermal shock were tested.The results show that the Ni-Ni/Cr-WC/Co coatings by electroless nickel and HVOF are compacter,higher bond strength than the PI-Ni/Cr-WC/Co coatings by HVOF.The former can resist 300 thermal cycles and have no visible changes,while the latter fail through delamination after 273 thermal cycles.The main reasons are that the layer of electroless nickel can be combined with the substrate through mechanical and atomic forces,and also with the Ni-Cr alloy layer by metallurgic and mechanical reaction,in addition efficiently relax the stress of the coating,so the bond strength of the graded coating is increased.
LU Ya-lin, HUANG Wei-chao, JIANG Hai-tao, LI Miao-quan. Effect of Process Parameters on Mechanical Behavior of Semi-solid Al-4Cu-Mg Alloy[J]. Journal of Materials Engineering, 2005, 0(5): 11-14.
Effects of deformation process parameters,including deformation temperature and the strain rate,on mechanical behavior of the semi-solid Al-4Cu-Mg alloy and the as-received were investigated through isothermal compression.The experimental results show that effects of deformation temperature and strain rate on peak stress of the Al-4Cu-Mg alloy are significant,and inappreciable on steady flow stress during the semi-solid state.Flow stress decreases with the increase of deformation temperature and the decrease of strain rate.The stress-strain curves of the semi-solid Al-4Cu-Mg alloy are similar to those of the as received at deformation temperature of 490℃.However,the semi-solid Al-4Cu-Mg alloy with spheroid grains and the as received alloy with irregular microstructure have different influence on mechanical behavior in the semi-solid state.
ZHANG De-ku, ZOU Gui-sheng, WU Ai-ping, LIU Gen-mao. Reinforcement of Ceramic Bonded Joints with Intermetallic Compounds——Microstructures and Interfacial Reaction of Joints[J]. Journal of Materials Engineering, 2005, 0(5): 15-18.
Si3N4 ceramics were bonded with Ag-Cu-Ti,in which Ti/Ni/Ti multi-interlayer was added in order to improve high temperature properties of the joints and decrease the residual stress.The results show that the joint comprises Ag-Cu matrix and intermetallic compounds with Ni,Ti,and Cu.The amount of Ni and Ti addition into weld has an important effect on status of intermetallic compounds and formation of interfacial reaction layer between weld and substrate.
DENG Mei-gen, YANG Bang-chao, HU Yong-da. Research on Preparation and Pseudocapacitance Characteristics of Nanosized NiO[J]. Journal of Materials Engineering, 2005, 0(5): 19-21,26.
Ni(OH)2 ultrafine powders were synthesized by precipitation transformation method.And nanosized NiO was prepared by calcining the as prepared Ni(OH)2 ultrafine powders.The samples were analyzed by transmission electron microscopy(TEM),thermal gravity(TG),X-ray diffraction(XRD),cyclic voltammetry and galvanostatic charge/discharge.The results show that particle size of the NiO is about 10nm.In an electrolyte of 0.5mol·L-1 KOH,the nanosized NiO has typical capacitive characterization in the potential region of-0.05～0.35V(vsSCE).At a current density of (2mA·cm-2,)the NiO has a specific capacitance of 243F·g-1.
CHEN Cui-xin, LI Wu-shen, WANG Qing-peng, FENG Bin, LIU Fang-ming, XUE Zhen-kui. Research on Influencing Factor of Impact Toughness in Coarse Grain Heat-affected Zone for X80 Pipeline Steel[J]. Journal of Materials Engineering, 2005, 0(5): 22-26.
Thermal simulating technology was used to simulate weld coarse grain heat-affected zone of pipeline steel X80 for the purpose of investigation on the influence of thermal cycle on low-temperature impact toughness.The experimental results showed that with the increase of t8/5,the crystal grains became coarser,small quantity of second phase particles precipitated and the phenomenon of aggregation occured.However,the impact toughness of specimens improved for the formation of a certain quantity of granular bainite and thin lath bainite when t8/5 was shorter than 6.8s.But if the t8/5 was longer than 6.8s,it would cause the lower percent of granular bainite,and the lath bainite would be coarser and tending parallel.The M-A constituent had little influence on toughness for its low percentage and small size.So it was concluded that lower heat input and suitable preheated temperature should be adopted to control grain size and microstructure morphology.
GAO Hou-xiu, WANG Wei-na, CHEN Quan-shui, LIU Shuang-yi. Preparation of One Dimensional Nanostructure of Cu-Zn-Al Alloy and Study of Growth Mechanism[J]. Journal of Materials Engineering, 2005, 0(5): 27-29,33.
At normal temperature and pressure,nanotubes were successfully prepared through substrate of Cu-Zn-Al alloy treated by mixed acid.Two kinds of nanotubes with different shape and component were found.The spectrum of EDX showed that main ingredient of them was Cu,Zn,Al and Si,Al,O.Most of their diameter were 20～50 nm,and the biggest length of them was about 1600nm.It was found that nanoparticles produced after mixed acid treating played important role in the process of nanotubes growth.The role of nanoparticles and growth mechanism of nanotubes were primarily studied by making use of growth model and TEM photos.
YANG Qing-hao, WANG Yang-yong, CHENG Guang-xu. Study on Property of Polyaniline in-situ Synthesized from Multiple Sulfonic Acids Medium[J]. Journal of Materials Engineering, 2005, 0(5): 30-33.
A new synthesizing technique,i.e.by using of a multiple acids system of dodecylbenzene sulfonic acid (DBSA) and p-toluene sulfonic acid (TSA) as the synthesizing media for in-situ preparation of polyaniline (PANI) instead of the conventional hydrochloride acid,was brought forward in order to enhance the solubility of PANI without losing the conductivity.The yield,the doping level,the solubility and the conductivity of the as-prepared PANI were investigated.By properly adjusting the molar ratio of DBSA/TSA in the synthesizing media,a PANI with conductivity of 1.1S/cm and solubility (mass fraction) of 70% in NMP,40%in acetone,26%in carbon tetrachloride and 19% in xylene was obtained.
JIANG Bin, XU Bin-shi, DONG Shi-yun, DING Pei-dao. Microstruture and Contact Fatigue Property of Nano-SiO2/Ni Composite Coating Prepared by Electro-brush Plating[J]. Journal of Materials Engineering, 2005, 0(5): 34-37,41.
The composite coating containing n-SiO2 particles was prepared by electro-brush plating and its contact fatigue life was examined by taking account of the effect of n-Cu particles on it.The results showed that fatigue life of the n-SiO2/Ni composite coating could exceed a million cycles and incorporation of n-Cu particles into the plating electrolyte greatly decreased the contact fatigue life of the coating.It was showed that the structure of the coating was presented as a continuous multilayer structure,leading to the initiation of fatigue cracks between layers and the propagation along the boundaries between the layers,and contact fatigue failure in less cycles.
WANG Rong-lin, WANG Zhi-fa, WANG Rui-sheng, BU Jing-long, LI Ru-chun, CHEN Yong-qiang. Preparation and Performance of Al2TiO5-ZrO2 Multiphase Material[J]. Journal of Materials Engineering, 2005, 0(5): 38-41.
The Al2TiO5-ZrO2 multiphase material was prepared at 1500℃×2h with α-Al2O3,TiO2,ZrO2 as raw materials and with MgO,SiO2,Fe2O3 as stability additives.The results show that thermal expansion coefficient of the sample at RT～1000℃ decreases gradually with increase of ZrO2 amount or the stability degree of ZrO2 in samples.This is different from behavior of ordinary multiphase material.The sample of ATZ-5 with bending strength of 39.15 MPa,water suction rate of 3.28% and thermal expansion coefficient of 4.46×10-6/℃ has excellent performance of thermal shock resistance and can resist 1.62 times thermal shock temperature interval of P-ZrO2.
LI Da-bing, PAN Hui, SUN Ji-sheng. Effect of Heat Treatment on γ' Phase and Property of Brazed Joints of K403 Alloy[J]. Journal of Materials Engineering, 2005, 0(5): 42-44.
Effect of post brazing heat treatment on γ' phase and property of the wide-gap brazed joints of K403 alloy was investigated.The results showed that there were γ' phases in the joint after diffusion treatment,and they were round.The sizes of γ' phases were larger in the base metal,and they became smaller from transition area to the brazing seam.After solid solution treatment at 1200℃,the γ' phases became square,but it was infavorable to property of the joints because new compound appeared.After aging treatment,γ' phases were square and deposited sufficiently,and it was favorable to compound diffusion.
ZHANG Bao-hong, ZHANG Xing, WANG Qiang, ZHANG Zhi-min, LI Bao-cheng. Influence of Plastic Deformation on Microstructure and Mechanical Properties of As-cast AZ31 Magnesium Alloy[J]. Journal of Materials Engineering, 2005, 0(5): 45-47,51.
In order to study the effect of plastic deformation on microstructure and mechanical properties of as-cast magnesium alloy,the isothermal compression experiment of as-cast AZ31 magnesium alloy was done.The microstructure and mechanical properties of original samples and deformed samples were investigated.Experimental results show that the grain size of as-cast AZ31 alloy can be dramatically refined by plastic deformation.When the deformation temperature increases,the tensile strength of deformed sample will fall.When temperature is same,the tensile strength of deformed sample will increase as increasing deformation,but it will not increase and will fall when the deformation exceeds a certain value.The tensile strength of the as-cast AZ31 alloy will dramatically increase by deformation at low temperature (210～240℃).
QIAN Bao-guang, GENG Hao-ran, GUO Zhong-quan, TAO Zhen-dong, TIAN Xian-fa. Effect of B4C on Mechanical Property and Oxidation Resistance for Copper Based Alloys[J]. Journal of Materials Engineering, 2005, 0(5): 48-51.
Several kinds of copper based electric contact materials were fabricated by powder metallurgy,and the effect of the B4C addition and powder size on mechanical property,oxidation resistance was studied.The results show that the hardness and abrasion resistance are improved when the B4C content is below 3%(mass fraction),at the same time,the oxidation resistance is decreased.The B4C content(≤2%) has little influence on the oxidation resistance.The effect is best on overall performance when the B4C content is 2%.The hardness,abrasion resistance and oxidation resistance are improved with reducing the powder size of B4C.
PAN Yan-feng, SHEN Yi-fu, GU Dong-dong, YANG Jia-lin, WANG Yang. Effect of Process Parameters on Balling During Direct Laser Sintering of 316 Stainless Steel Powders[J]. Journal of Materials Engineering, 2005, 0(5): 52-55.
A series of experiments were carried out with direct metal laser sintering (DMLS) for the 316 stainless steel powders.During the laser sintering,due to the large liquid phase viscosity and surface tension,the balling effect occurred when the molten did not wet the solid metal particle and the underlying substrate.This resulted in a rough and bead-shaped surface,obstructing a smooth layer deposition.The balling effect of 316 stainless steel powder was studied,and the effects of process parameters,such as laser power,scan rate,and layer thickness,on the success of laser sintering were discussed.The results showed that increasing scan rate and decreasing laser power can minish balling effect to a certain extent.
WEI Jian, LI Ke-zhi, LI He-jun, LI Zheng-jia, FU Qian-gang. Fabrication of Anodic Alumina Membrane[J]. Journal of Materials Engineering, 2005, 0(5): 56-59,64.
Anodic alumina membrane (AAM) was fabricated by two-step anodizing process in oxalic acid solution.The effects of electrolytic temperature and electropolishing on the final alumina textural properties were researched.The morphology and crystalline structure of the as-received AAM were investigated by scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) system and x-ray diffraction (XRD).The highly ordered hexagonal pores grown in AAM with diameters of 50~70 nm and thickness of several tens of micrometers pack with each other closely and the AAM is an amorphous alumina structure.In addition,the stabilization of electrolytic temperature and electropolished treatment are propitious to form ideally ordered hexagonal pores in AAM.
LIN Ying-ying, PAN Hong-si, LI Miao-quan. Hydrogen Treatment and Its Effect on Superplasticity of Titanium Alloys[J]. Journal of Materials Engineering, 2005, 0(5): 60-64.
Hydrogen treatment is a new technique in metal forming which can improve the microstructure of titanium alloys,workability and mechanical properties with the hydrogen reversible alloying.Hydrogen absorption in titanium alloys could increase the proportion of the β-phase,decrease the flow stress and improve the superplasticity of titanium alloys,therefore reduce the requirement of deformation temperature and strain rate for superplastic forming.The ultra-fine grain with less than 1μm obtained through combining severe plastic deformation with hydrogen treatment has good superplasticity at lower deformation temperature and higher strain rate.It is a new effective method for solving the problem for hard to deform of titanium alloys.
